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Old Jul 03, 2009, 11:48 AM
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Lipo Storage Voltage and Dead Battery Information

About once a week (or oftener) someone posts a question on how, or whether to, revive an over discharged Lipo battery or What is the best storage voltage.
Here are some of the recent threads on that subject. I'm sure you will find an answer to your question in one of them.

Best Storage Voltage is 40-50% charged or about 3.78-3.85V/cell.

(Remember, overdischarged lipos are damaged goods and the safety precautions recommended for lipo packs should be followed. Using damaged packs is not recommended)
Over-discharging can cause internal damage to electrodes and current collectors
(i.e., dissolution of copper) , can lead to lithium plating if the cell is recharged
(particularly, if the cell is repeatedly over-discharged), and can ultimately lead to thermal runaway"


Consider this before doing any recovery attempts.

(HOW TO) Recovering over discharged lipos
http://www.rcgroups.com/forums/showthread.php?t=1072324

dead lipo how to charge it
http://www.rcgroups.com/forums/showthread.php?t=1002464

Can I save this lipo?
http://www.rcgroups.com/forums/showthread.php?t=1072215
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Old Jul 07, 2009, 08:18 AM
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Hoppy... Hoppy... Hoppy... tsk... tsk...

What makes you think they will pay any attention now? Lonely and lazy noobs will always start new threads on the subject even if 5 identical ones precede.

Like death and taxes...
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Old Jul 07, 2009, 12:21 PM
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There will alway be people who will start a new thread even if the answer to their question is on the first page of this forum, but I think the stickys have helped A LOT. The "Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports" has almost 1/3 million views. That's an average of about 147 views PER DAY. You have to think that many of those people found the answer to their questions, and as a result, did not start another thread.

I think that this thread would be a valuable sticky, and one specifically aimed at "What's the best charger" would be good too.

Dan
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Old Jul 07, 2009, 12:31 PM
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Old Aug 22, 2010, 11:12 AM
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Those other threads recommend charging around 0.3C until the battery is above "too low" threshold for the LIPO charger. I found a manual for a LIPO cell once (but I've since lost it), and it recommended charging "really slow". I think it mentioned 0.1C, but can't be sure. Anyway
- Charge really slowly as long as they are below 3.0V. (0.1C recommended)
- Damage is done by TIME below 3.0V. So recharge with this procedure ASAP when you notice you've left your battery on.
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Old Oct 15, 2010, 02:29 AM
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Yeah...
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Old Oct 21, 2010, 11:24 PM
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What a Great Thread!

Just a couple of months back and plus being new to any type of elec. flying except for a GWS Tiger Moth that was all stock with no upgrades I had went on the battery section of the forums and ask if there was anyway at all I could save my Brand New Lipo that I had left plugged in to the plane by mistake and it drained the battery to the point to where it showed zero voltage. The answer I got was to cut the plugs off and disgard the new pack (3 cell) and that''s just what I did. Being my very first Lipo and brushless set-up that really hurt!! If I had read this post in time just maybe I could have saved the pack? It was just a 20.00 pack but just being a week old and now was told it was junk kinda hurt a little. I sure hated cutting those plugs off that new pack but that's what I was told to do and that's what I did. Thanks for this info and maybe next time it happens (Which I don't think it will) as now atleast I know and very careful about leaving one pluged up!! Now if I'm very careful just maybe I can save a pack or atleast have a chance...

Again, Thanks for the info and instrutions on how to do this! VERY good informantion that I will not forget and you can take that to the BANK!!

Best Regards,
Ben Morrow
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Old Oct 22, 2010, 08:09 AM
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Ben,
Tossing a pack that had been under load for 1 week and was at 0V was not a bad thing to do.
Once the cells go below 2.5V the battery starts to undergo permanent damage which can not be undone.
Here's a reference on what happens inside the pack once the voltage/temp goes outside the safe operating window. http://www.mpoweruk.com/lithium_failures.htm
Running the pack below 2.5V/cell causes the copper anode to dissolve.

The best hope for "saving" cells is when the pack has gone just a little under the range where the charger won't turn on and it hasn't been at that low level for very long.
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Old Oct 22, 2010, 11:33 AM
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Thanks hoppy.....

Post has been removed. Sorry hoppy!
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Old Oct 22, 2010, 03:04 PM
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I don't remmember recommending any units from 2dodrc but that's neither here nor there.
I suggest you post this question as a new thread in the forum, you'll probably get more responses.
Cell checkers will work with any manufacturers pack - the only "but" is that the connectors must match up.
For instance, Polyquest uses a 5 pin connector for 3s packs using pins 1,3,4,5 as I recall whereas Hobbyking and many others use a 4 pin connector in a 1,2,3,4 combo for 3 cells. TP uses a smaller 4 pin connector using pins 1,2,3,4. If all your packs match the pin wiring on your tester, no problem. Otherwise you'll need adapters to match them up.
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Old Oct 22, 2010, 07:33 PM
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Sorry hoppy......

hoppy, I've made a mistake and placed this post in the wrong thread. I guess that would make me one of those once a week postings about how to bring a battery back to life after it's been drained dead. I'll try and copy and paste my post and place it where it should be under a thread that I started. But, however I have enjoyed reading your thread! It's just that my pack was way too far gone and dead for help.

Again, Sorry for placing this post under the wrong thread.

Best Regards,
Ben
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Old Nov 01, 2010, 12:39 PM
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Thanks!! excellent information.
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Old Nov 11, 2010, 03:02 AM
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Quote:
Originally Posted by rewolff View Post
Those other threads recommend charging around 0.3C until the battery is above "too low" threshold for the LIPO charger. I found a manual for a LIPO cell once (but I've since lost it), and it recommended charging "really slow". I think it mentioned 0.1C, but can't be sure. Anyway
- Charge really slowly as long as they are below 3.0V. (0.1C recommended)
- Damage is done by TIME below 3.0V. So recharge with this procedure ASAP when you notice you've left your battery on.
I've revived a few turnigy and Rhino packs by charging them at 100ma.

I sat the batteries in a lipo safe during the charge. i once upon a time tried to revive a lipo by charging it at 2c.......there was a fire.

100ma worked for me
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Old Nov 14, 2010, 09:18 AM
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This is great battery info... i think there is almost impossible to charge a dead lipo, should try the info, tks
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Old Nov 16, 2010, 03:41 PM
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re: re-soldering battery leads

Can anyone advise me on the correct and safe procedure for re-soldering a charger lead to a cell?

Thanks,
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